[CH2:1]([CH:5]1[CH2:13][C:12]2[C:7](=[CH:8][CH:9]=[C:10]([O:14][CH3:15])[CH:11]=2)[C:6]1=[O:16])[CH2:2][CH2:3][CH3:4].N12CCCN=C1CCCCC2.[CH:28]([C:30]([CH2:32][CH3:33])=[O:31])=[CH2:29]>O1CCCC1>[CH2:1]([C:5]1([CH2:29][CH2:28][C:30](=[O:31])[CH2:32][CH3:33])[CH2:13][C:12]2[C:7](=[CH:8][CH:9]=[C:10]([O:14][CH3:15])[CH:11]=2)[C:6]1=[O:16])[CH2:2][CH2:3][CH3:4]A solution of crude 2-butyl-5-methoxy-1-indanone (218 mg, 1 mmol) in tetrahydrofuran (THF, 2 mL) was treated with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 0.030 mL, 0.2 mmol) and ethyl vinyl ketone (EVK, 0.200 mL, 2 mmol). The resulting solution was stirred under a nitrogen atmosphere at room temperature for 16 hours, followed by heating in an oil bath at 60° C. for 24 hours. Evaporation of the solvent under vacuum left a residue that was shown by NMR to be approximately a 1:1 mixture of starting material and product. The residue was purified by preparative layer chromatography on three 0.1×20×20 cm silica gel GF plates using 5% EtOAc in CH2Cl2 as developing solvent. The product band was eluted with EtOAc to provide 2-butyl-5-methoxy-2-(3-oxo-pentyl)-1-indanone (84 mg) as an oil.
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